ReleaseNotes: profile-driven cache prefetching. Text by Mircea!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_80@354554 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index ddf12f61de300b3e2008a396258a2dd7010c7fed..7adfd13c54f3ff93dd3e962b42264629668c63e3 100644 (file)
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -62,6 +62,24 @@ Non-comprehensive list of changes in this release
 
 * Added support for labels as offsets in ``.reloc`` directive.
 
+* Support for precise identification of X86 instructions with memory operands,
+  by using debug information. This supports profile-driven cache prefetching.
+  It is enabled with the ``-x86-discriminate-memops`` LLVM Flag.
+
+* Support for profile-driven software cache prefetching on X86. This is part of
+  a larger system, consisting of: an offline cache prefetches recommender,
+  AutoFDO tooling, and LLVM. In this system, a binary compiled with
+  ``-x86-discriminate-memops`` is run under the observation of the recommender.
+  The recommender identifies certain memory access instructions by their binary
+  file address, and recommends a prefetch of a specific type (NTA, T0, etc) be
+  performed at a specified fixed offset from such an instruction's memory
+  operand. Next, this information needs to be converted to the AutoFDO syntax
+  and the resulting profile may be passed back to the compiler with the LLVM
+  flag ``-prefetch-hints-file``, together with the exact same set of
+  compilation parameters used for the original binary. More information is
+  available in the `RFC
+  <https://lists.llvm.org/pipermail/llvm-dev/2018-November/127461.html>`_.
+
 .. NOTE
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